This invention relates to an improved heat exchange apparatus, particularly of the type used to cool hot oil generated through the use of industrial machinery. More particularly, the invention concerns a heat exchange apparatus, for which heat exchange air flows past heat exchange tubes, employing a novel heat exchange tube retainer to hold the heat exchange tubes firmly in place and preferably, although not necessarily, deflect air toward heat exchange fins on the heat exchange tubes.
A typical heat exchange apparatus includes a support member and several heat exchange tubes with heat exchange fins attached to and surrounding the periphery of the central portion of the tubes. Each of the tubes are supported at each end within the support member. The support member is generally a preconstructed rectangular frame with apertures in two opposing sides within which the heat exchange tubes are inserted during assembly. The heat exchange tubes are sometimes secured within the apertures of the support member by welding the ends of the tubes within the apertures. Other methods of securing the tubes within the support member, such as force fitting the tubes into grommeted frame apertures, allow for later removal of the heat exchange tubes from the frame for repair, replacement, or cleaning. Representative of prior art heat exchange apparatus having removable heat exchange tubes is Murray U.S. Pat. No. 3,391,732. Such constructions of the prior apparatus have certain deficiencies, however.
For example, in order to insert the heat exchange tubes into the apertures within the preconstructed frame, the axial length of the central finned portion of the heat exchange tubes must be substantially shorter than the distance between the apertures within which the tube is mounted. After assembly of the apparatus, there is, therefore, a sizable portion of the tube within the inside perimeter of the frame which is not surrounded by a heat exchange fin. These non-finned portions of the heat exchange tubes not only serve little or no heat exchanging function but also become paths of at least resistance for air flow through the apparatus. Air which would otherwise remove heat by passing through a finned portion of a heat exchange tube thus escapes through the non-finned portion, decreasing the overall heat exchanging efficiency of the apparatus.
Another problem with the prior art apparatus is in securing the tubes firmly within the frame. Permanent welds make tube replacement a very difficult process and are vulnerable to fatigue failure. Force fitting permits easier replacement of the tubes on an individual basis and eliminates fatigue failure, but force fitted tubes may loosen through vibration, jarring, or extreme changes in temperature during use of the apparatus.
The extensive and continually expanding field of application for such heat exchange devices has created a strong demand to improve the efficiency, reliability, and ease of assembly and disassembly of the heat exchange apparatus. The present invention achieves improvement in each of those ends.